This project investigates the neural bases of abstract rule learning and exemplar-specific learning in the Artificial Grammar (AG) learning task. It is hypothesized that the caudate is involved in abstract rule learning and the hippocampus is involved in exemplar-specific learning. This project will also examine whether the AG task is an implicit or explicit learning task. Although it is typically characterized as an implicit task, there is both neural and behavioral evidence that suggests that some of the learning acquired may be acquired explicitly. Finally, the project will examine the performance of Parkinson's Disease patients on this learning task. Because of the specific methodological design used, their ability to learn abstract rules and to use exemplar-specific information can be independently examined. Together, these experiments will contribute to our fundamental knowledge of learning, and this knowledge should, in turn, be used to further the development of treatments and diagnostic tests for patient populations.